The catalytic dehydrogenation of hydrocarbons, particularly short chain hydrocarbons with 2-6 C atoms, is carried out in known fashion, by passing the hydrocarbons adiabatically through fixed bed reactors, in either pure form or diluted with an inert gas. A plurality of fixed bed reactors operated in parallel may be used. In general the dehydrogenation catalyst is comprised of aluminum oxide with additives such as, e.g., chromium oxide or other metal oxides or mixtures of same (see Ger. OSs Nos. 36 14 854 and 36 20 481, and U.S. Pat. Nos. 2,943,067 and 2,419,997).
Such metal oxides are prepared, e.g., with aqueous ammonia solution. Often suitable solutions of metal salts are applied onto support materials such as aluminum oxide.
About 8 years ago, various groups of researchers undertook the study of ceramic powders produced by a novel method, wherein suitable gaseous starting compounds were reacted under CO.sub.2 laser irradiation to form pulverulent solids.
The powders formed have the following properties: Small particle diameter, uniform shape, narrow particle size distribution, high purity, low degree of agglomeration, and high surface activity (see J. Am. Ceramic Soc., 65, 7:324 ff.).
In U.S. Pat. No. 4,343,687, among other things the production of metal oxide powders by irradiating suitable starting compounds with a pulsed IR laser of a frequency not absorbed by the reaction mixture is described. The resulting products are said to be suitable for catalytic purposes. According to this method, e.g., a Cr.sub.2 O.sub.3 powder is produced on a support, in a closed static cell, by a laser-induced reaction between chromyl chloride (CrO.sub.2 Cl.sub.2) as the oxidant and hydrogen as the reaction partner, wherewith the reaction is initiated by at least one laser pulse of 2 J/cm.sup.2.